Control method of a refrigerator

ABSTRACT

An embodiment according to the present invention is to provide a control method of a refrigerator that can operate a compressor before a start of a defrost operation and during a predetermined time to supply a high-temperature hot gas to an evaporator. With the control method of the refrigerator according to the embodiments of the refrigerator, the compressor is driven immediately before the defrost operation and the blower fan cooling the compressor stops, such that the high-temperature hot gas can be supplied to the evaporator, thereby increasing the defrost efficiency.

TECHNICAL FIELD

The embodiment relates to a control method of a refrigerator.

BACKGROUND ART

Generally, a refrigerator is consumer electronics that can store food at low temperature in an inner storage space shielded by a door. The refrigerator uses cool air generated by heat exchange with a refrigerant circulating a freezing cycle to cool the storage space, such that it is configured to store the stored food at an optimum state.

The refrigerator includes an evaporator that generates cool air. Frost may be generated in the evaporator by the frosting and freezing of moisture.

When frost is generated in the evaporator, a problem of sanitation may occur and cooling efficiency is degraded to increase power consumption. In order to prevent the problem, the refrigerator includes a defrost heater to remove frost (hereinafter, referred to as defrost).

At a step of a defrost operation, the defrost heater is operated and an operation of components that configure a freezing cycle such as a compressor and a blower fan stops. The defrost operation can be continued during a setting temperature or until a temperature of the refrigerator reaches the setting temperature.

Meanwhile, the defrost operation can be repeatedly performed in consideration of an open and close frequency, an open and close accumulative time, an operation ratio of the compressor, etc.

The defrost operation of the related art is performed by a method that heats a high-temperature refrigerant by the defrost heater or a method that bypasses the high-temperature refrigerant discharged from the compressor to the evaporator side by a switching valve and heats it with a hot gas. Two methods can be simultaneously adopted as needed.

According to the methods of the related art, the temperature in the refrigerator is increased during the defrost operation, such that food is damaged.

DISCLOSURE OF INVENTION Technical Problem

An embodiment according to the present invention is to provide a control method of a refrigerator that can operate a compressor before a start of a defrost operation and during a predetermined time to supply a high-temperature hot gas to an evaporator.

In addition, the present invention is to provide a control method of a refrigerator that can vary a rotation speed of a compressor according to a temperature of the open air during a defrost operation.

Solution to Problem

There is provided a control method of a refrigerator according to an embodiment of the present invention, including: a normal operation step that is repeatedly turned-on/off by a compressor and performs a normal freezing operation; an operation step before defrost that is selectively performed according to whether a start signal of a defrost operation is input and controls an turn-on/off operation of a blower fan cooling the compressor according to whether a temperature of the open air reaches a first setting temperature before the start signal of the defrost operation is input; and a defrost operation step that controls to bypass a refrigerant discharged from the compressor to an evaporator side by the input of the start signal of the defrost operation and selectively performs a high-temperature defrost operation or a low-temperature defrost operation according to whether the open temperature reaches a second setting temperature, wherein it returns to the normal operation step after the defrost operation step is ended.

There is provided a control method of a refrigerator according to another embodiment of the present invention, including: a normal operation step that generates cool air by a refrigerant circulating a compressor, a condenser, an expander, and an evaporator; a defrost operation step that periodically operates according to an input of a start signal of the defrost operation and selectively performs the defrost of the evaporator according to whether the temperature of the evaporator side reaches a third setting temperature; and an operation step before defrost that is performed before the defrost operation step and when a setting time does not pass before the input of the start signal of the defrost operation, turns-on a blower fan cooling the compressor and when the setting time passes, controls the turn-on/off of the blower fan according to whether the temperature of the open air is higher than the first setting temperature.

Advantageous Effects of Invention

With the control method of the refrigerator according to the embodiments of the refrigerator, the compressor is operated immediately before the defrost operation and the blower fan cooling the compressor stops, such that the high-temperature hot gas can be supplied to the evaporator, thereby increasing the defrost efficiency.

In addition, the refrigerant, which is discharged from the compressor and is supplied to the evaporator, can be supplied to the refrigerator before the defrost operation, thereby preventing the temperature in the refrigerator from suddenly increasing during the defrost operation.

Further, the rotation speed can be varied according to the temperature of the open air during the defrost operation, such that the high-temperature hot gas can be discharged even when the temperature of the open air is lower than the setting temperature.

Consequently, when the temperature of the open air is lower than the setting temperature, the defrost stuck in the evaporator can be smoothly removed by the high-temperature hot gas discharged from the compressor, thereby making it possible to increase the defrost efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cycle diagram showing a configuration of a refrigerator cycle of a refrigerator according to an embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of a refrigerator according to an embodiment of the present invention;

FIG. 3 is a flowchart showing a control method of a refrigerator according to an embodiment of the present invention;

FIG. 4 is a flow chart showing an operation method before defrost among the control methods of the refrigerator according to the embodiment of the present invention;

FIG. 5 is a flow chart showing an operation method before defrost among the control methods of the refrigerator according to the embodiment of the present invention;

FIG. 6 is a graph showing a change in input voltage according to a time during a high-temperature defrost operation with reference to the control method of the refrigerator according to the embodiment of the present invention; and

FIG. 7 is a graph showing a change in input voltage according to a time during a low-temperature defrost operation with reference to the control method of the refrigerator according to the embodiment of the present invention.

MODE FOR THE INVENTION

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be utilized and that logical structural, mechanical, electrical, and chemical changes may be made without departing from the spirit or scope of the invention. To avoid detail not necessary to enable those skilled in the art to practice the invention, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

FIG. 1 is a cycle diagram showing a configuration of a refrigerator cycle of a refrigerator according to an embodiment of the present invention and FIG. 2 is a block diagram showing a configuration of a refrigerator according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, a compressor 10, a condenser 20, an expander 30, an evaporator 40, and a liquid refrigerant tank 50, which configures a freezing cycle, are sequentially connected in series in a refrigerator 1 according to an embodiment of the present invention to circulate the refrigerant, thereby making it possible to operate the freezing cycle.

The refrigerator 1 further includes a bypass pipe 60 that bypasses the refrigerant discharged from the compressor 10 to an inlet side of the evaporator 40.

A switching valve 70, which is connected to a pipe connecting the compressor 10 and the condenser 20, is provided at one end of the bypass pipe 60.

The switching valve 70 selectively branches a high-temperature and high-pressure refrigerant discharged from an outlet side of the compressor 10 to the condenser 20 or the evaporator 40. The switching valve 70 is configured to connect to the compressor 10, the condenser 20, and the bypass pipe 60, respectively.

The blower fan 11 cooling the compressor 10 is provided at one side of the compressor 10. The blower fan 11 is configured to cool the compressor 10 while rotating together with the operation of the compressor 10 during the normal operation of the refrigerator 1.

The blower fan 11 blows the open air to the condenser 20 side, such that the heat exchange can be easily performed in the condenser 20.

One side of the evaporator 40 is provided with a cooling fan 41 that forcibly blows a refrigerant generated by the heat exchange with the refrigerant in the evaporator 40 to the refrigerator side.

One side of the evaporator 40 is provided with a defrost heater 80 that is heated during the defrost operation of the refrigerator 1 and removes frost stuck in the evaporator 40.

The refrigerator 1 is further provided with a first temperature sensor 91 that senses the temperature of the evaporator 40 and a second temperature sensor 92 that senses the temperature of the open air.

The first temperature sensor 91 may be disposed at one side of the evaporator 40 and the second temperature sensor 92 may be disposed at one side of a machine room or a main body of the refrigerator in which the compressor 10 and the condenser 20 are provided.

In addition, the refrigerator 1 includes a counter 90 that counts an operation time of a plurality of components configuring the refrigerator and a controller 100 that receives a signal from the first and second temperature sensors 91 and 92 and the counter 90 to control the operation of the compressor 10, the blower fan 11, the cooling fan 41, and the defrost heater 80, etc.

Hereinafter, the control method of the refrigerator according to the embodiment of the present invention having the above-mentioned configuration will be described in detail with reference to the accompanying drawings.

FIG. 3 is a flowchart showing a control method of a refrigerator according to the embodiment of the present invention, FIG. 4 is a flow chart showing an operation method before defrost among the control methods of the refrigerator according to the embodiment of the present invention, and FIG. 5 is a flow chart showing an operation method before defrost among the control methods of the refrigerator according to the embodiment of the present invention.

Referring to FIGS. 3 to 5, under the normal operation environment of the refrigerator 1, when the compressor 10 is operated, the refrigerator is circulated and the blower fan 11, the cooling fan 41, etc., can be controlled.

The rotating speed of the compressor 10 can be controlled according to an input load. To this end, the compressor 10 may include an inverter-type compressor of which the number of rotations can be changed according to the input voltage.

The operation time of the compressor 10 can be controlled according to the input load. In detail, after the temperature of the refrigerator reaches a predetermined level or the compressor 10 is operated during a setting time or more, the compressor 10 is operated again after it stops during a predetermined period. The above process is continuously repeated (S100).

Moisture of the open air can be stuck on a surface of the evaporator 40 during the general normal operations and thus, frost may occur. Frost can be generated on the surface of the evaporator 40 by the moisture of food that is stored in the refrigerator.

The surface temperature is lowered by the continuous operation of the freezing cycle, such that the frost stuck on the surface of the evaporator 40 is frozen and continuously grown. As a result, the heat exchange performance of the evaporator 40 is degraded and the freezing performance of the refrigerator is degraded.

Therefore, in order to prevent this, the defrost operation is needed to remove the frost frozen in the evaporator 40.

The defrost operation may increase the temperature of the refrigerator, such that it may be performed at a predetermined period to maintain the storage performance.

The accumulative operation time of the compressor 10, the open frequency of the door, and the open accumulative time of the door, etc, can be counted in the counter 90 and the timing of the defrost operation can be determined based on the counted time.

The defrost operation starts by the start signal of the defrost operation output from the controller 110 and the start signal of the defrost operation can be output at a timing that needs the defrost operation according to a predetermined period in the process of performing the normal operation (S100).

During the defrost operation using the hot gas of the compressor, the operation of the blower fan 11 that cools the compressor 11 can stop in order to secure the temperature (high temperature) of the hot gas supplied to the evaporator 40.

Meanwhile, in order to increase the efficiency of the defrost operation, the operation before defrost can be performed before the defrost operation is performed (S200).

The operation before defrost includes a defrost signal input determining step (S210) that confirms whether the start signal of the defrost operation is input during the performance of the normal operation.

When the start signal of the defrost operation is input, the defrost operation is performed and when the start signal of the defrost operation is not input, it is determined whether the defrost operation passes the setting time T from the time when the defrost operation is performed. For example, the setting time T can be set to approximately 30 minutes in consideration of the defrost efficiency. In other words, the setting time T can be set to 30 minutes before a time when the defrost operation starts to perform (S220).

In other words, when it is assumed that the defrost operation is performed at a period of 10 hours, it is determined whether the setting time reaches a time when about one and a half hours passes after the start signal of the previous defrost operation is input.

Meanwhile, when it does not pass the setting time T before the start signal of the defrost operation is input at the setting time determining step (S220), the blower fan 11 maintains a turn-on state during the operation of the compressor 10.

The blower fan 11 performs a normal operation until it passes the setting time before the time when the start signal of the defrost operation is input. In other words, since the blower fan 11 does not reach a specific time before the defrost operation, it does not have to be turned-off in order to perform the defrost operation (S230).

On the other hand, if it is determined at the setting time determining step (S220) that the setting time T before the start signal of the defrost operation is input passes, a setting temperature determining step, which compares the temperature of the open air detected by the second temperature sensor 92 with the first setting temperature D1, is performed (S240).

At this time, the first setting temperature D1 can be set to approximately 15° C. When the temperature of the open air is higher than about 15° C., the temperature of the hot gas necessary for the normal frost can be secured even though the blower fan 11 does not stop.

Therefore, when the temperature of the open air detected by the second temperature sensor 92 is higher than the first setting temperature D1, the blower fan 11 maintains a turn-on state during the operation of the compressor 10 (S230) and performs the normal operation until it reaches the setting time T before the start signal of the defrost operation is input (S100).

On the other hand, when the temperature of the open air detected by the second temperature sensor 92 is lower than the first setting temperature D1, the compressor 10 is in a turn-on state to be operated and the blower fan 11 stops (S250).

In this case, the force cooling of the compressor 10 is not performed and the refrigerant discharged from the compressor 10 is in a higher-temperature state. The operation state can be maintained during the setting time.

In other words, when the temperature of the open air is lower than the first setting temperature D1, the operation of the blower fan 11 stops when the compressor 10 is operated before the setting time T of the time when the defrost operation starts.

In this case, the temperature of the refrigerant discharged from the compressor 10 can be increased and the more efficient defrost can be performed at the time when the defrost operation starts.

The cool air can be supplied to the refrigerator by the operation of the compressor 10 before the defrost operation, such that the sudden increase in the temperature of the refrigerator can be prevented during the defrost operation [operation step before defrost (S200)].

Meanwhile, when the start signal of the defrost operation is input from the controller 100, the defrost operation starts. When the start signal of the defrost operation is input, the temperature of the open air detected by the second temperature sensor 92 is compared with the second setting temperature D2.

When the detected temperature of the open air is higher than the second setting temperature D2, the high-temperature defrost operation is performed and when the detected temperature of the open air is lower than the second setting temperature D2, the low-temperature defrost operation is performed.

At this time, the second setting temperature D2, which is a reference of differentiating the high-temperature defrost operation and the low-temperature defrost operation, can be set to about 3° C.

When the temperature of the open air is lower than 3° C., the defrost efficiency cannot but degrade as compared with the case where the temperature of the open air is relatively high. Therefore, in order to maintain the appropriate defrost efficiency according to the temperature of the open air, the scheme of the defrost operation is divided on the second setting temperature D2 and performed (S310).

First, in the case of the high-temperature defrost operation where the temperature of the open air is higher than the second setting temperature D2, the compressor 10, the blower fan 11, and the cooling fan 41 stop (S311 and S312).

It is determined that the temperature of the evaporator 40 reaches the third setting temperature D3 by the first temperature sensor 91.

The third setting temperature D3 can be set to about 3° C. It can be determined that the defrost is performed when the temperature of the evaporator 40 side is approximately 3° C. On the other hand, when the temperature of the evaporator 40 side is lower than approximately 3° C., the defrost operation is continuously performed (S320).

Herein, in the defrost operation, the defrost scheme by the defrost heater 80 and the defrost scheme by the hot gas can be simultaneously performed.

In detail, when the temperature of the evaporator 40 side is lower than the third setting temperature (at steps S311 and S312, the operations of the compressor 10, the cooling fan 41, and the blower fan 11 are turned-off, the temperature of the evaporator 40 side is in a sub-zero state), the defrost heater 80 is turned-on.

The switching valve 70 is switched to flow the refrigerant from the outlet of the compressor 10 to the inlet of the evaporator 40 and the compressor can be operated at a low speed.

Since the temperature of the open air is in the higher state than the second setting temperature D2, the refrigerant for defrost can be supplied to the evaporator 40 side even though the compressor 10 is operated at a low speed. Herein, low speed” can be defined as forming low speed as compared to the operation of the compressor at step S343.

The high-temperature and high-pressure refrigerant (hot gas) discharged from the compressor 10 is guided to the evaporator 40 through the bypass pipe 60. The hot gas is filled in the evaporator 40 such that the surface of the evaporator 40 can be heated and the removal of the frost frozen on the surface of the evaporator 40 starts.

Meanwhile, after the switching valve 70 is switched, the compressor 10 can be operated after approximately 5 seconds passes. The switching valve 70 and the entire system can be protected by supplying the high-temperature and high-pressure refrigerant by the compressor 10 at a time difference with the switching of the switching valve 70.

The defrost heater 80 can be operated immediately before and after the switching of the refrigerant flow path by the operation of the switching valve 70. In particular, at the early time when the defrost is performed, the evaporator 40 or a portion adjacent the evaporator 40 is heated at higher heat, such that the defrost heater 80 is operated, thereby making it possible to more rapidly perform the defrost.

Meanwhile, the above-mentioned defrost operation is repeatedly performed until the temperature detected by the first temperature sensor 91 is higher than the third setting temperature D3 (S321, S322, and S323).

When the temperature detected by the first temperature sensor 91 is higher than the third setting temperature D3, the high-temperature defrost operation is ended. In other words, the operations of the compressor 10 and the defrost heater 80 stop and the switching is performed by the switching valve 80.

The refrigerant discharged from the compressor 10 again flows to the condenser 20 according to the switching of the switching valve 70 (S324, S325, S326).

The freezing cycle is in the normal operation state by the path change of the switching valve 70 and returns to the normal operation step (S100) that performs the general normal operation again after ending the high-temperature defrost operation [defrost operation step (S300)].

Meanwhile, in the case of the low-temperature defrost operation where the temperature of the open air is higher than the second setting temperature D2, the compressor 10, the blower fan 11, and the cooling fan 41 stop (S331 and S332).

It is determined that the temperature of the evaporator 40 side reaches the third setting temperature D3 by the first temperature sensor 91.

The third setting temperature D3 can be set to about 3° C. It can be determined that the defrost is performed when the temperature of the evaporator 40 side is approximately 3° C. On the other hand, when the temperature of the evaporator 40 side is lower than approximately 3° C., the defrost operation is continuously performed (S340).

In detail, when the temperature of the evaporator 40 side is lower than the third setting temperature (at steps S331 and S332, the operations of the compressor 10, the cooling fan 41, and the blower fan 11 are turned-off, the temperature of the evaporator 40 is in a sub-zero state), the defrost heater 80 is turned-on.

The switching valve 70 is switched to flow the refrigerant from the outlet of the compressor 10 to the inlet of the evaporator 40 and the compressor can be operated at a high speed. In other words, the defrost scheme by the defrost heater 80 and the defrost scheme by the hot gas can be simultaneously performed.

Since the temperature of the open air is in the lower state than the second setting temperature D2, the compressor 10 is operated at a high speed, such that a large amount of refrigerant necessary for defrost can be supplied to the evaporator 40 side.

The high-temperature and high-pressure refrigerant (hot gas) discharged from the compressor 10 is guided to the evaporator 40 through the bypass pipe 60 and the surface of the evaporator 40 is heated, thereby making it possible to remove the frost.

The defrost heater 80 can be operated immediately before and after the switching of the refrigerant flow path by the operation of the switching valve 70. In particular, it can be controlled to supply a large heat amount at the early time when the defrost is performed.

Meanwhile, the above-mentioned defrost operation is repeatedly performed until the temperature detected by the first temperature sensor 91 is higher than the third setting temperature D3 (S341, S342, and S343).

When the temperature detected by the first temperature sensor 91 is higher than the third setting temperature D3, the low-temperature defrost operation is ended. In other words, the operations of the compressor 10 and the defrost heater 80 stop and the switching is performed by the switching valve 80.

The refrigerant discharged from the compressor 10 again flows to the condenser 20 according to the switching of the switching valve 70 (S344, S345, and S346).

FIG. 6 is a graph showing a change in input voltage according to a time during a high-temperature defrost operation with reference to the control method of the refrigerator according to the embodiment of the present invention.

Referring to FIG. 6, the compressor 10 is operated to sequentially pass a first period, a second period, a third period, and a fourth period during the high-temperature defrost operation and the change in the operation speed (rotation speed) and rotation speed of the compressor 10 is controlled differently at each period.

In detail, when power is applied to the compressor 10, an initial input voltage of the compressor 10 is set to Vo at the first period. A magnitude of Vo may be 120V (rms).

The compressor 10 continuously (linearly) increases the input voltage for approximately t1, which reaches V1. Herein, t1, which is a time that is previously set, may be approximately 6 seconds.

The size of V1 may be 130V (rms) and may correspond to the highest rotation speed during the high-temperature defrost operation.

The voltage input to the compressor 10 is maintained to approximately t2 as the magnitude of V1 at the second period. Herein, t2, which is a time that is previously set, may be approximately 3 minutes.

Consequently, the compressor 10 continuously increases the input voltage after the operation and maintains the highest rotation speed (input voltage V1) for the previously set time t1 to t2.

The temperature of the refrigerant discharged from the compressor 10 is increased in the state where the highest rotation speed is maintained, such that the defrost can be efficiently performed.

However, when the compressor 10 maintains the highest rotation speed (input voltage V1) for a long time, the pressure of the refrigerant discharged from the compressor 10 increases and the pressure of the suction side of the evaporator 40 increases, thereby generating noise.

Therefore, it controls to lower the rotation speed of the compressor 10 after passing approximate t2 that is a threshold value of a noise allowable level. In other words, the rotation speed of the compressor 10 is reduced at the highest rotation speed at the instant that the pressure of the refrigerant sucked into the evaporator 40 side exceeds the setting pressure.

In order to prevent the noise of the compressor at the third period, the rotation speed of the compressor 10 is gradually (linearly) lowered from the highest rotation speed (input voltage V1).

In detail, the input voltage of the compressor 10 is continuously reduced at V1 and the input voltage may be V2 at the time that passes t3 from the start time of the defrost operation. Herein, t3, which is a previously set time, may be set to approximately 14 minutes after the operation of the compressor and V2 is a predetermined time and may be set to approximately 100V (rms).

As the rotation speed of the compressor 10 is reduced, the pressure of the refrigerant discharged from the compressor 10 and the pressure of the suction side of the evaporator 40 are reduced, thereby reducing the noise.

In summary, the rotation speed of the compressor 10 is controlled in the patterns Vo to V2 shown in FIG. 6, the temperature level of the hot gas discharged from the compressor 10 can be maintained in an allowable range, thereby making it possible to prevent the noise of the compressor 10.

At the fourth period, the input voltage of the compressor 10 is maintained at V2. At this time, the defrost operation is performed.

The rotation speed of the compressor 10 may be maintained at the lowest rotation speed (input voltage V2) up to a time (t4) when the defrost operation is ended. The condition where the defrost operation is ended is that the temperature of the evaporator 40 reaches the third setting temperature D3 as shown in FIG. 5.

The input voltage supplied to the compressor 10 together with the ending of the defrost operation is turned-off and the compressor 10 stops.

As described above, the rotation speed (input voltage Vo to V2) of the compressor 10 is proposed as one embodiment and may be proposed as other previously set values according to and the defrost heat amount and the capacity of the compressor 10.

FIG. 7 is a graph showing a change in input voltage according to a time during a low-temperature defrost operation with reference to the control method of the refrigerator according to the embodiment of the present invention.

FIG. 7 shows the change in the input voltage of the compressor 10, that is, the change in the input voltage at the first period and the second period according to the change in time during the low-temperature defrost operation.

Referring to FIG. 7, the compressor 10 is rotated at an initial rotation speed (initial input voltage V0 ) by the voltage input to the compressor 10 while the low-temperature defrost operation is performed. Herein, the initial input voltage may be set to 120V (rms).

The input voltage applied to the compressor 10 is continuously (linearly) increased to a time t5 that is previously set at the first period. Herein, the time t5 may be approximately 20 seconds after the operation of the compressor 10.

After t5 passes, the compressor 10 can be rotated at the highest rotation speed (input voltage V3). Herein, V3, which is a previously set value, may be set to approximately 180V (rms).

The compressor 10 is rotated at a relatively high speed by V3, that is, the input voltage of 180V (rms) (comparing with V1 of FIG. 6), thereby making it possible to discharge the relatively higher-temperature and higher-pressure refrigerant than the refrigerant temperature during the high-temperature defrost operation.

Even though the high-temperature and high-pressure refrigerant is discharged from the compressor 10, the low-temperature defrost operation is performed at the state where the temperature of the open air is low, such that the pressure of the suction side of the evaporator 40 is relatively lower, thereby reducing the noise.

The rotation speed of the compressor 10 is constantly maintained after it reaches the highest rotation speed (input voltage V3) at the second period. When the temperature of the evaporator 40 is approximately 3° C. that is the third setting temperature D3, the supply of voltage to the compressor 10 stops at time t6 and the operation of the compressor 10 stops.

In summary, the voltage input to the compressor 10 is increased from the first Vo to V3 during the low-temperature defrost operation and the rotation speed of the compressor 10 maintains the highest rotation speed V3 for a predetermined time.

When the ending condition of the low-temperature defrost operation is satisfied, that is, the temperature of the evaporator 40 reaches the third setting temperature (third setting temperature or more), the voltage supplied to the compressor 10 is turned-off and the operation of the compressor 10 stops.

As described above, the operation of the blower fan 11 is controlled according to the temperature value of the open air of the refrigerator, such that the freezing cycle can be efficiently operated.

In addition, the high-temperature defrost operation and the low-temperature defrost operation can be selectively performed according the temperature value of the open air, such that the defrost of the evaporator 40 can be efficiently performed.

Further, the defrost heater 80 and the hot-gas defrost operation can be simultaneously performed according to the temperature value of the evaporator 40, such that the defrost efficiency can be increased.

INDUSTRIAL APPLICABILITY

With the control method of a refrigerator according to the embodiment as constituted above, a compressor is operated immediately before the defrost operation and the blower fan cooling the compressor stops, such that the high-temperature hot gas can be supplied to the evaporator, thereby increasing the defrost efficiency. Therefore, its industrial applicability is noticeable. 

1. A control method of a refrigerator, comprising: a normal operation step that is repeatedly turned-on/off by a compressor and performs a normal freezing operation; an operation step before defrost that is selectively performed according to whether a start signal of a defrost operation is input and controls an turn-on/off operation of a blower fan cooling the compressor according to whether a temperature of the open air reaches a first setting temperature before the start signal of the defrost operation is input; and a defrost operation step that controls to bypass a refrigerant discharged from the compressor to an evaporator by the input of the start signal of the defrost operation and selectively performs a high-temperature defrost operation or a low-temperature defrost operation according to whether the open temperature reaches a second setting temperature, wherein it returns to the normal operation step after the defrost operation step is ended.
 2. The control method of a refrigerator according to claim 1, wherein the start signal of the defrost operation is periodically input according to the set time interval and the operation step before defrost is continuously performed until the start signal of the defrost operation is input.
 3. The control method of a refrigerator according to claim 1, wherein the operation step before defrost controls the turn-on/off of the blower fan according to whether the setting time before the input of the start signal of the defrost operation passes.
 4. The control method of a refrigerator according to claim 3, wherein when the setting time does not pass, the blower fan is turned-on, when the setting time passes, the blower fan is controlled to be turned-on/off according to whether the temperature of the open air reaches the first setting temperature.
 5. The control method of a refrigerator according to claim 4, wherein when the temperature of the open air is higher than the first setting temperature, the blower fan is controlled to be turned-on, and when the temperature of the open air is lower than the first setting temperature, the blower fan is controlled to be turned-off and the compressor is operated.
 6. The control method of a refrigerator according to claim 1, wherein the defrost operation step performs the high-temperature defrost operation when the temperature of the open air is higher than the second setting temperature and performs the low-temperature defrost operation when the temperature of the open air is lower than the second setting temperature.
 7. The control method of a refrigerator according to claim 6, wherein the rotation speed of the compressor at the high-temperature defrost operation is formed to be higher than the rotation speed of the compressor at the low-temperature defrost operation.
 8. The control method of a refrigerator according to claim 1, wherein the high-temperature defrost operation and the low-temperature defrost operation are selectively performed according to whether the temperature of the evaporator is higher than the third setting temperature.
 9. The control method of a refrigerator according to claim 1, wherein at the high-temperature defrost operation, the rotation speed of the compressor is maintained for the predetermined time after being linearly increased from the initial rotation speed to the highest rotation speed and then linearly reduced.
 10. The control method of a refrigerator according to claim 1, wherein at the low-temperature defrost operation, the rotation speed of the compressor is maintained until the defrost operation is ended after being linearly increased from the initial rotation speed to the highest rotation speed.
 11. A control method of a refrigerator, comprising: a normal operation step that generates cool air by a refrigerant circulating a compressor, a condenser, an expander, and an evaporator; a defrost operation step that periodically operates according to an input of a start signal of the defrost operation and selectively performs the defrost of the evaporator according to whether the temperature of the evaporator reaches a third setting temperature; and an operation step before defrost that is performed before the defrost operation step and when a setting time does not pass before the input of the start signal of the defrost operation, turns-on a blower fan cooling the compressor and when the setting time passes, controls the turn-on/off of the blower fan according to whether the temperature of the open air is higher than the first setting temperature.
 12. The control method of a refrigerator according to claim 11, wherein the defrost of the evaporator is simultaneously performed with an operation of a defrost heater and the hot-gas defrost that supplies the refrigerant from the discharge side of the compressor to the inlet side of the evaporator.
 13. The control method of a refrigerator according to claim 12, wherein the compressor at the hot-gas defrost is decelerated at the highest rotation speed at the instant that the refrigerant pressure sucked into the inlet side of the evaporator exceeds a setting pressure.
 14. The control method of a refrigerator according to claim 11, wherein at the defrost operation, the low-temperature defrost operation that operates the compressor at low speed and the high-temperature defrost operation that operates the compressor at higher speed than the compressor of the low-temperature defrost operation are selectively performed according to whether the temperature of the open air is higher than a second setting temperature.
 15. The control method of a refrigerator according to claim 14, wherein during the high-temperature defrost operation, the compressor is sequentially operated at: a first period that is increased from an initial rotation speed to a highest rotation speed; a second period that maintains the highest rotation speed during a predetermined period after reaching the highest rotation speed; and a third period that is reduced from the highest rotation speed to the lowest rotation speed; and a fourth period that maintains the rotation speed until the defrost operation is ended after reaching the lowest rotation speed.
 16. The control method of a refrigerator according to claim 15, wherein during the low-temperature defrost operation, the compressor includes: a first period where is increased from an initial rotation speed to a highest rotation speed; and a second period that maintains the highest rotation speed during a predetermined period after reaching the highest rotation speed, when the temperature of the evaporator reaches the third setting temperature, the voltage supplied to the compressor is turned-off. 